The SAM E70/S70/V70/V71 features a security bit based on the GPNVM bit 0. When security is enabled, any access to the Flash, SRAM, core registers and internal peripherals, either through the SW-DP, the ETM interface or the Fast Flash Programming Interface, is blocked. This ensures the confidentiality of the code programmed in the Flash.
This security bit can only be enabled through the command “Set General-purpose NVM Bit 0” of the EEFC User Interface. Disabling the security bit can only be achieved by asserting the ERASE pin at 1, and after a full Flash erase is performed. When the security bit is deactivated, all accesses to the Flash, SRAM, Core registers, Internal Peripherals are permitted.